Folding bicycles?
Mountain bikes suspension systems
Not that I like the subject, but there are some weapons that have sophisticated mechanisms too.
Also see Dough Chiang's work on Star Wars and Robota.

In anything at all, perfection is finally attained not when there is no longer anything to add, but when there is no longer anything to take away. - Antoine de Saint-Exupery

You should definitively give a look at Per Mollerupâ€™s â€œCollapsiblesâ€ book, which covers pretty much all types of collapsible mechanism. All collapsible mechanism are regrouped in categories with a lot of illustrated examples. Its really a book that is oriented towards design